feat: complete image-sharing appWSGI Tutorial

app/app.py

@@ -1,7 +1,19 @@
+import os
+
 import falcon
 
-from .images import Resource
+from .images import Collection, Item, ImageStore
 
-app = application = falcon.App()
 
-app.add_route('/images', Resource())
+def create_app(image_store):
+    app = falcon.App()
+    app.add_route('/images', Collection(image_store))
+    app.add_route('/images/{name}', Item(image_store))
+    return app
+
+
+def get_app():
+    storage_path = os.environ.get('LOOK_STORAGE_PATH', './images')
+    image_store = ImageStore(storage_path)
+    return create_app(image_store)
+

app/images.py

@@ -1,10 +1,34 @@
+import io
+import os
+import re
+import uuid
+import mimetypes
+
 import falcon
 import msgpack
 
 
-class Resource:
+ALLOWED_IMAGE_TYPES = (
+    'image/gif',
+    'image/jpeg',
+    'image/png',
+)
+
+
+def validate_image_type(req, resp, resource, params):
+    if req.content_type not in ALLOWED_IMAGE_TYPES:
+        msg = 'Image type not allowed. Must be PNG, JPEG, or GIF'
+        raise falcon.HTTPBadRequest(title='Bad request', description=msg)
+
+
+class Collection:
+
+    def __init__(self, image_store):
+        self._image_store = image_store
 
     def on_get(self, req, resp):
+        # TODO: Modify this to return a list of href's based on
+        # what images are actually available.
         doc = {
             'images': [
                 {
@@ -16,3 +40,63 @@ class Resource:
         resp.data = msgpack.packb(doc, use_bin_type=True)
         resp.content_type = falcon.MEDIA_MSGPACK
         resp.status = falcon.HTTP_200
+
+    @falcon.before(validate_image_type)
+    def on_post(self, req, resp):
+        name = self._image_store.save(req.stream, req.content_type)
+        resp.status = falcon.HTTP_201
+        resp.location = '/images/' + name
+
+
+class Item:
+
+    def __init__(self, image_store):
+        self._image_store = image_store
+
+    def on_get(self, req, resp, name):
+        resp.content_type = mimetypes.guess_type(name)[0]
+
+        try:
+            resp.stream, resp.content_length = self._image_store.open(name)
+        except IOError:
+            # Normally you would also log the error.
+            raise falcon.HTTPNotFound()
+
+
+class ImageStore:
+
+    _CHUNK_SIZE_BYTES = 4096
+    _IMAGE_NAME_PATTERN = re.compile(
+        '[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\.[a-z]{2,4}$'
+    )
+
+    def __init__(self, storage_path, uuidgen=uuid.uuid4, fopen=io.open):
+        self._storage_path = storage_path
+        self._uuidgen = uuidgen
+        self._fopen = fopen
+
+    def save(self, image_stream, image_content_type):
+        ext = mimetypes.guess_extension(image_content_type)
+        name = '{uuid}{ext}'.format(uuid=self._uuidgen(), ext=ext)
+        image_path = os.path.join(self._storage_path, name)
+
+        with self._fopen(image_path, 'wb') as image_file:
+            while True:
+                chunk = image_stream.read(self._CHUNK_SIZE_BYTES)
+                if not chunk:
+                    break
+
+                image_file.write(chunk)
+
+        return name
+
+    def open(self, name):
+        # Always validate untrusted input!
+        if not self._IMAGE_NAME_PATTERN.match(name):
+            raise IOError('File not found')
+
+        image_path = os.path.join(self._storage_path, name)
+        stream = self._fopen(image_path, 'rb')
+        content_length = os.path.getsize(image_path)
+
+        return stream, content_length